I grew up on a blacktop crew, literally. I have been outside since in the University of Science Music and Culture, and as a lineman.
Drink before you are thirsty. If your pee is orange, its way past time. Leave the ice at the poles. Cool yes if you can, not cold. Ice water makes you thirsty, can give you a headache and mess up your guts and shock your system. Sports drinks as a supplement, not the primary liquid. Coffee is actually OK. You do NOT get rid of more than you take in, that is a fallacy. You only go more because you drank more.
Hats that breathe, sunglasses, sunscreen. I use SPF Scottish (100). Quick dry light color pants. Light color T shirts.